Apparatus for making strings



Jan. 6, 1942.

H...W. ROBERTS APPARATUS FOR MAKING STRINGS 3 Sheets-Sheet l Filed March 11, 1940 I fiafozd W l olea zg v ATTORNEY.

N%N Q Q8 Jan. 6, 1942.

H. W. ROBERTS APPARATUS FQR MAKING STRINGS FiledrMarch 11, l940 3 Sheets-Sheet 2 Wad (Z a 50 ATTORNEY.

Jan. 6, 1942. v H. w. ROBERTS 2,268,343

APPARATUS FOR MAKING STRINGS Filed March 11, 1940 3 ShetS-Sheet 3 IN VENT OR.

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ATTORNEY Patented Jan. 6, 1942 APPARATUS FOR MAKING STRINGS Harold W. Roberts, La, Grange, 111., assignor to Thompson Manufacturing Company, Chicago, 111., a corporation of Illinois Application Marchll, 1940, Serial No. 323,321

15 Claims.

This invention relates in general to the method of twisting gut strings for tennis,badminton and the like, and has more particular reference to a new and improved apparatus and method for twisting a plurality of plies in one direction at one end of a string, and twisting all of the plies together by rotating, them at the other end of the string.

Among the objects to be attained in carrying out and utilizing this new and improved process and apparatus are:

To produce plies of the same diameter, the same length and under the same tension when twisting;

To cause the plies to take a definite position in the string and to pull toward the center thereof;

To reduce the total diameter and thus to ofier a narrow section to. outside abrasive action;

To change a flat ribbon to a round string in making up the plies;

To allow the use of a core of this material;

To eliminate the necessity of closelywatching the ply length and tension in makin strings; and.

To definitely mark or identify a string product; and r I In general to produce thestructure and to employ the novel method herein shown and described in making gut strings.

In the accompanying drawings illustrating a andv Fig. 6 is a side elevation of the. twisting head. At present gut strings are. made from ribbons obtained by slitting casings. from end to end.

f These ribbons vary in width from fiiito of an inch and in thickness from .002 to ;006 when dry. Even though they are selected for size and grouped for width of ply as closely as practical there are great variations within each string. A surficient number of ribbons are tied together on a loop at one end to make, a completed string of the desired gauge. At the other end, the ribbons are loose, they are put on a hanging bench, straightened out, and an attempt isv made to' the same tension on each ply before the loop is I in before any twisting takes place.

suming that the plies are of equal length and tion to produce a string of the desired length. This .produces a group of loose pliesof supposedly the same length fastened to loops at each end.

In the condition thusassembled the plies go through considerable processing, including dy- Even, as

under the same tension at the time they. are hung, furtherprocessing affects each ply differently; some shrink and. others stretch, so that at the end of the processing when they are ready to be twisted the plies are not of uniform'length and will not twist under uniform, tension. The slack in some plies is taken up by the twisting before any revolutions are made in the string, which by no means produces the desired equal lengthand equal tension on each ply. One end loop is placed on a spinning hook and the other end is held stationary and as rotations are continued the string is twisted, allowing the plies to take any position they will until the string has the desired amount of twist to produce a round ut string whendry. v

A suitable apparatus and mechanism for pr'acticing this method comprises a motor driven hook or loop for attachment at one end of a string and a rotatable head with ,a pluralityof grippers for separately engaging the ribbons at the other end of the string. The mechanismis so arranged that it is possible to rotate the ribbons in 'one direction, and to rotate all of the, ribbons from the other'end of the string in a reverse direction. Improved means is also provided forattaching the ribbons, rotating the separate plies,

and releasing the plies when the string twisting is completed.

Plies and. ribbonsare synonymous terms, each individual ribbon or ply'i s twisted anti-clockwise and then sufiicientribbons or plies to make a string. of desired gauge are grouped together and connected at one end to a loop or hook I l operated .by means of a shaft l2 connected to a motor I3 mounted at one end of a bench or other suitable support l4. V

At the baseof the cone the plies are connected to a number of grippers l5 mounted in a spinning head H5 at theother end of the bench and actuated for spinning movement by a connected moplaced on the opposite end at the required positor I]; The motors l3 and IT are conveniently the gripper gears 38.

controlled by electrical connections (not shown) and switches l8 and I9 adjacent the twisting head.

The twisting head comprises a circular disc having an outer flange 2| and teeth 22 corresponding in number with a plurality of spaced perforations 23 for receiving the grippers IS.

A hub 24 of the disc is rotatable about a bearing sleeve 25 extending from a bearin 26 formed as a part of a supporting base or upright standam 21. Rotatable within the sleeve is a driving shaft 28 with a bearing 29 between it and the sleeve at the disc end and having a gear 30 secured to it at the other end beyond the bearing portion 26. Meshing with the gear 30 is a driving pinion 3| secured to a shaft 32 having fast and loose pulleys 33 and 34 thereon, the former being driven by a belt 35 from the driving pulley of motor I 1.

One of the grippers I5 is rotatably mounted in a bearing 36 in each of the outer perforations 23 of the disc 20. Each gripper comprises a sleeve 31 having a pinion 38 secured to or formed integral therewith and projecting from the sleeve intermediate the ends thereof. Near one end the sleeve has a recess 39 with a bayonet slot 40 at its inner end, and a slot 4| at its outer end extending to the extremity of the sleeve. The interior recess 42 at this end of the sleeve is beveled to receive a correspondinglybeveled tip 43 of a gripper rod 44 movable in the bar havin a larger portion 45 fitting loosely in the opening of the sleeve and substantially traversing the recess 39. A stud 46 projects from the outer end of the enlarged portion and is adapted to be seated and engaged by the bayonet slot 4|! against the tension of a spring 41 located in the space between the interior of the sleeve 31 and a reduced portion 48 of the rod, bearing against the enlarged portion 35 at one end and against a small'collar 49 in the end of the sleeve at the other end, held in place by a set screw 50, the collar also serving as a bearing for this end of the rod 44. At this end of the rod and spaced from the end of the sleeve is-aprojecting collar or head 5| for moving the rod against the tension of the spring 41 as hereinafter set forth.

The tapered end 43 of the rod is forced into the correspondingly tapered recess 42 of the sleeve by the spring 41 but the-slot 4| extends from the edge of the sleeve to the central opening. at the end thereof so that the flat gut ribbons for forming the plies, or the plies themselves, may be readily inserted through the slot 4| when the rod is held back against the spring 41 and the inner edges 52 of the recess 39 near the end of the sleeve are rounded to receive and .allow the extremities of the gut ribbons or plies to extend therefrom without tending to cut them. Ifit is necessary to maintain the gripper rod in retracted position for any length of time it may be moved against the spring 41, seating the stud 46 in bayonet slot 40 where it will be held until released by a slight rotation of the rod.

Secured to the shaft 28 by a fastening nut 53 or other suitable means is a gear having a hub portion 54 and a ring gear 55 engaging all of This gear is-seated in a recess formed by the flange 2| of the disc 20 and is enclosed by a face plate 56 secured to the flange and having bearings 51 therein surrounding each one of the gripper sleeves 31 for holding the gripper in place and for common rotation of all of the grippers by means of the gear 55.

In order to bring each gripper successively into 5 place for attaching the ribbons or plies thereto the disc 20 is rotated step by step by means of the teeth 22. This may be effected by means of a lever 58 having a short arm with a pawl 59 pivoted thereto and pressed into engagement with the teeth 22 by a spring 60. The other arm of the lever is connected by a rod 6| to a pedal 62 conveniently located below the bench I4 for engagement by the foot of an operator and as the pedal is depressed the lever advances the disc until the pawl engages an eccentrically adjustable stop 63 whereupon the pedal may be returned for the next engagement of the pawl with one of the teeth 22.

A hand stop or positioning device consisting of a locking pawl 64 may be pivoted on the base 21 and adapted to engage any one of the teeth 22 with a rod 65 connected at one end intermediate the ends of the pawl and having a grip or handle 66 at its other end. In this rod are notches 61 adapted to engage a fixed stop 68 so that by operating the handle the pawl 64 may be moved from a position free from the disc to a locking position engaging the disc and held in either position by one of the notches 61.

In order to open or release each gripper for the attachment of gut ribbons or plies each time the gripper .head is rotated one step, an operating device is preferably connected with the pedal 62. This device comprises a holder 16 supported by an arm 1| extending from a bracket 12 at one side of the base 21. In the holder is a short shaft 13 extending endwise through the holder and having a nut 14 at one end for securing it in place. Mounted on the shaft and extending through the other end of the holder is a sleeve 15 having a sprocket 16 secured thereto and rotated in opposite directions by a chain 11. At one end of the chain is a spring 18 connected to some fixed part, as the base 21, and at the other end of the chain it is connected by a rod 19 with the pedal 62. Thus downward pressure on the pedal rotates the sleeve 15 in one direction and the action of the spring 18 returns the pedal to its upper position and rotates the sleeve in the other direction.

As the sleeve 15 is rotated it is moved endwise in the holder bymeans of a worm gear 86 secured thereto, the thread of which engages with a stud 8| projecting thereinto from the holder. At the inner end of the sleeve an arm 82 is secured which is rotated and moved endwise as the sleeve is rotated, the end of the arm having notches 83 and 84 at its edges and being of a length to engage under each of the heads 5| ofthe gripping devices so that each depression of the pedal;62 moves the twisting head one step in advance and at the same time engages the arm 82 with the next gripper to be attached to the gut ribbons or plies, withdrawing the gripping rod 40 from its engagement with the end recess 42 and thus opening the slot 4| thereof for the free insertion, arrangement and disposition of the ply ribbons therein. The release of pressure on the pedal 62 allows the spring 18 to return the gripping rod to gripping position and positions the arm 82 for engagement with the head of the next gripper. In its endwise movement the sleeve 15 will be projected on the shaft 13 and from the end of the holder the distance determined by the. pitch of the thread of the worm gear 80.

The tension of the ribbons or plies may be easily adjusted and made practically the same in drawing them through the grippers and after all of the grippers are th us attached the rib- 'the gri-ppers hens and plies will form an elongatedco'ne as represented in Fig. 1, the difference in initial pressure being evident from the difference in sag of the plies which may then be adjusted so that all the ribbons or plies will have substantially the same pressure. At-this time the plies may all be separately twisted byrotating the grippers by means of the gear 55" which is controlled by the motor l1. When the desired amount of twist has been given to each of 'the plies they arerounded, the tension is'increased due to the shortening of the length of the ply on account of twisting, and each of the plies is of substantially the same length and tension. Y

The hook or loop at the other end of the string is then'rotated to turrr the hook or loop II in a relatively opposite direction, that is, if the plies are twisted counter-clockwise when looking from the end of the twisting" head, the string is twisted in a clockwise direction so that the pull of all the plies will be toward the center of the string.

Twisting the string is then continued at intervals until the desired amount of turns have been made in the full length of the string, at

:pl'ete strings;

, 3 for further twisting of the com- Iclaim: I 1 .An apparatus ior making gut strings,

comprising a rotatable head having gut ribbon and'ply grippers spaced apart about the periphery of the head and individually rotatable which time the ends of the plies or ribbons will be connected to the grippers in a short flat (zone. The apex of this cone is then tightly engaged and the next operation is to remove or disengage all of the ribbons or plies from the gripper head. This' is accomplished in a single operation and a loop is made of the ends of the ribbons or plies to keep them from untwisting.

The means for disengaging or releasing the grippers from the ribbons or plies comprises a plate 85 surrounding the bearing sleeve 25 and of a diameter slightly less than the distance between opposite rods 44 in the disc Thus the outer periphery of the plate is of sufficient diameter to engage all of the heads 5| at the inside thereof so that by moving the plate 85 away from the disc 20 all of the rods 44 will be withdrawn from the outer ends of the grippers, thus releasing the gripped ends of the ribbons or plies. To accomplish this operation the central portion of the plate 85 is mounted upon a collar 86 slidable upon the sleeve and engaged at its opposite sides by a yoke 81 in the form of a lever having a pivot 88 between its ends secured to the support 21 and its opposite end connected by a rod 89 with a pedal 90. The depression of this pedal causes the movement of the plate 85, engaging the heads 5| of all the grippers and moving them against the pressure of their springs 41 so that as soon as the pedal 90 is released all of the grippers will be returned to their gripping positions. The engagement of this plate 85 at the inner edges of the rods 44 does not .affeet or interfere with the operation of the releasing device which is operated by the other lever or pedal 62.

When a twisted string is thus disconnected from the gripper head the twisting of the string is complete, and the string is ready to be further processed or treated as desired, by smoothing, filling or polishing it, depending upon the surface or use for which it is intended.

A central hook 96 is threaded or otherwise connected to the end of the driving shaft 28 at the center of the spinning head, thus providing for the attachment of a central distinguishing core for the exclusive marking, and also providing means to which the gripper ends of the spun plies may be attached after removal from therein for engagement at one end of the ribbons or plies, means for rotating the head and twisting together all the separately twisted plies,

and meansat their other ends for engaging all of the ribbons or plies for rotating and twisting them together at the same time.

2'. In an; apparatus for making twisted gut strings, a rotatable head having grippers spaced about the periphery and individually rotatable therein for engagement of gut ribbons or plies at one end thereof, means for rotating the grippers in the head and twisting the plies in one direction, means for rotating the head and with lit the gripper twisted plies at one end, and means for'engaging all of the ribbons or plies at their other ends for rotating them at the same time in the opposite direction.

3-. In an apparatus for making twisted gut strings, a rotatable head having grippers spaced apart about the outer edge thereof adapted to engage the ends; of gut ribbons and plies-means for rotating thegrippers, and means for advancing the head stepby step to bring each of "the grippers successively into a predetermined position. H v

4. In an apparatus for making twisted gut strings, a rotatable head having means to advance it step by step in one direction, a plurality of grippers mounted about the periphery of the head, each gripper having a membermovable therein for engaging one extremity of gut ribbone and separately rotatable therein for making a round ply of the ribbons.

5. In an apparatus formaking twisted gut strings, a string-engaging head comprising a plurality of grippers disposed at spaced distances about the outer edge of the head, each gripper comprising relatively fixed and movable parts for engaging the ends of a plurality of gut ribbons, means for separately rotating the grippers and the head for uniting the gripper twisted ribbons, at the head end andmeans connected atthe other end of the ribbons for twisting them all together at the same time.

6. In a machine for twisting gut strings, means for engaging one end of all of the gut ribbons, a rotatable head at the other end having means for engaging groups of ribbons or plies, means for rotating the head in a step by step movement, means to rotate theribbon engaging means for twisting them individually to form circular plies, means at the other ends of the plies for twisting them all together, and means at the head of the ribbons for holding this end of the twisted plies in fixed position while the other end of the plies is being twisted.

'7. In a machine for twisting gut strings, a rotatable head, a plurality of gut ribbon grippers rotatably mounted in the head, each gripper comprising a sleeve with a gear thereon, means in the head for engaging the gears of the grippers independently of the rotation of the head,

the rotation of the head twisting together the rotatable head, means about the outside of the head for releasably engaging gut string ribbons comprising a sleeve mounted in the head having a recess with a slot leading thereto at one end for inserting gut string ribbons, and a springpressed bolt movable in the sleeve to engage and grip ribbons disposed in the recess of the sleeve, the recess and bolt end being tapered.

9. In a machine for twisting gut strings, a rotatable head, means about the outside of the head for releasably engaging gut string ribbons comprising a sleeve mounted in the head having a recess at one end for receiving gut string ribbons, a spring pressed bolt movable in the sleeve to engage and grip ribbons disposed in the recess of the sleeve, means for rotating the head in a step by step movement, and means in connection with the gripper for withdrawing the bolt to open the recess in the sleeve for the admission of gut strings when the head is advanced in a step by step movement.

10. In a machine for twisting gut strings, a rotatable head, a plurality of gut ribbon grippers rotatably mounted in the head, each gripper comprising a rotatable sleeve and a springpressed bolt longitudinally movable in the sleeve, means in connection with the head for rotating the grippers independently of the rotation of the head, and means engageable with the bolts for moving them together longitudinally of the sleeves for releasing gut ribbon connections therewith.

11. In a machine for twisting gut strings, a gut ribbon gripper and ply twister comprising a sleeve having a gear thereon for rotating it, a recess in the sleeve with .a slot opening thereto from one end for inserting gut ribbons therein, a bolt longitudinally movable in the sleeve to engage and grip gut ribbons threaded through the slot and located in the recess, and a spring for pressing the bolt in engagement with the ribbons.

12. A structure in accordance with claim 11 in which the end of the bolt is tapered and the inner end of the sleeve is correspondingly tapered to fit the bolt at the recessed end of the sleeve into which the bolt is pressed by the spring thereof;

'13. A structure in accordance with claim 11 in which the recess near one end of the sleeve has a slot extending therefrom to the end, and an opposite bayonet locking recess, and the bolt has a stud extending therefrom into the recess adapted to be engaged with the bayonet locking notch against the pressure of the spring.

14. A gut string gripper in accordance with claim 11 in which the bolt has a projection into the recess for limiting relative rotation of the bolt with respect to the sleeve, and the end of the bolt opposite the recess in the sleeve has a collar attached thereto for moving the bolt rearwardly against the pressure of the spring between the bolt and its sleeve.

15. In a machine for twisting gut strings, a rotatable head, a plurality of gut ribbon grippers rotatably mounted about the outer edge of the head, means for advancing the head in a step by step movement, each gripper comprising a sleeve'rotatable in the head, and a springpressed stem longitudinally movable in the sleeve with an engageable collar at one end of the bolt outside of the sleeve, means for engaging the collars of successive bolts as the head is rotated in a step by step movement for moving each bolt against the tension of its spring, and means engageable with all of the collars at the same time for moving them against the tension of their springs to release gut ribbons from the other ends of the grippers.

HAROLD W. ROBERTS. 

